The present invention relates to a fuel injector assembly, and more particularly to a fuel injector assembly with a shell configured to allow fluid communication between an exterior surface of a body and a fuel passageway for particular weld integrities.
In a known system, the assembly of a fuel injector involves the insertion of a body into a shell. The body has an outside diameter which is slightly larger than the inside diameter of the shell. By this arrangement, an interference fit between the body and the shell is achieved. A lubricant is introduced on either or both of an exterior surface of the body and an interior surface of the shell to ease the insertion of the body into the shell. The body is hermetically attached to the interior surface of the shell by a weld. It is believed that both the use of a lubricant on and the use of an interference fit between the body and the shell lead to a few disadvantages. For example, during the forming of the weld, air and lubricant trapped between the body and the shell may become heated and expand in volume. The use of an interference fit between the body and the shell hinders the escape of the expanded air and lubricant. The integrity of the weld may be compromised, as the heated air and lubricant may expand through the weld. For these reasons, the use of an interference fit between a body and a shell of a fuel injector assembly necessitates a visual inspection of the weld.
It is further believed that due to the use of an interference fit between the body and the shell, pressure measurements upstream and downstream from the weld may not indicate whether the weld forms a hermetic seal. A satisfactory test result may only indicate that the interference fit between the body and the shell prevents the escape of a fluid.